Wireless communications between peripherals and Personal Computers (PCs) is rapidly growing in popularity. Many wireless systems transfer data in only one direction, from a transmitter to a receiver, but not in the other direction. Examples of such systems include most Human Interface Devices (HIDs), such as mice, keyboards and game controllers. These devices are implemented most cost-effectively with a transmit-only radio, because generally a radio transmitter is much less costly to implement than a receiver.
However, many of these systems are implemented using 2-way wireless links, primarily because of the difficulty of associating a given transmitter with a corresponding receiver without the benefit of a back channel. This difficulty is a result of the uncertain nature of wireless communication. Wireless systems typically have a choice of using multiple channels, in order to allow many transmitter/receiver pairs to operate in the same physical location.
Depending on the type of access scheme used by the wireless system, these channels may use different frequencies, timeslots or codes. For example, wireless devices may use Frequency Division Multiple Access (FDMA), Time Divisional Multiple Access (TDMA), or Code Division Multiple Access (CDMA) channel access. Some frequencies may be subject to interference from other wireless systems or unintentional radiators of Radio Frequency (RF) energy.
The presence of a back channel in a 2-way radio system allows the implementation of automatic channel search algorithms, which enable a group of wireless devices to automatically bind to each other without further intervention after a user initiates the binding process.
One-way radio systems have much less satisfactory binding procedures. A first conventional solution uses channel selector switches. The user sets a switch on both a transmitter and a receiver to the same position, and evaluates whether or not performance is satisfactory. This requires the user to manually test each switch setting, and make an often subjective judgment about the relative quality of the wireless link.
A second conventional solution uses bind buttons where the user presses a bind button on both the transmitter and receiver. The transmitter transmits test data on a first frequency, and the receiver listens for the test data on that first frequency. If the test data is received correctly, the receiver gives basic feedback to the user for example by illuminating a green LED. If no test data is received, or the data contains too many errors, the receiver indicates this by flashing a red LED. In this case, the user then presses the bind button on both transmitter and receiver a second time and the process repeats for another channel. The process may require third, fourth, etc. button presses if the earlier channels do not deliver satisfactory performance.
This solution has found acceptance in 27 MHz wireless Human Interface Device (HID) applications, but is the major cause of product support calls and store returns for such products. The process becomes even more unfriendly if more than one transmitter needs to bind to the same receiver. In this case, the binding process is typically undertaken first with one transmitter, and the user counting the number of iterations performed before binding is successful. The user then has to press the bind button the same corresponding number of times on the second, third, etc wireless devices. If there are more than a small number of channels and devices, this process becomes very cumbersome.
This type of binding procedure is unlikely to be successful in 2.4 GHz wireless devices, that typically have seventy to eighty channels. A large number of wireless channels are necessary due to the presence of wireless Ethernet (WiFi), Bluetooth, cordless phones and other wireless devices that require the availability of many channels in any given location.
If a radio receiver had a more sophisticated user interface than a single bind button and 1 or 2 LEDs, then it might be possible to greatly simplify this process. The transmitter and receiver could test every channel, and the User Interface (UI) on the receiver could display simple step by step instructions which the user could follow to configure each transmitter to use the best channel.
Consumers have also become accustomed to electronic devices which work “out of the box” with little or no user intervention. If user intervention is required, the user expects to be guided through it, step by step, by on-screen instructions. An obvious technique for providing such a user interface in a HID application would be to provide an installation program and driver with the wireless system. The program could run on the host computer display screen and could then guide the user through the process described above. However, this would significantly detract from the “plug and play” ideal of modern Personal Computer (PC) peripherals.
The cost of the Compact Disc (CD) would partially offset the cost benefit of using a 1-way rather than 2-way radio system. In addition, many end-users are accustomed to plugging Universal Serial Bus (USB) devices into their PC, and having them work without installing drivers or software applications. Another problem exists when the user misplaces the CD after initial installation of the wireless system. It would be troublesome if the user then needed to install the wireless system on a different PC.
These are just some of the reasons why wireless HID manufacturers are reluctant to adopt solutions which require the installation of drivers and/or software applications. Such OEMs typically opt to incur the cost of using 2-way wireless systems, rather than incur the inconvenience and product support cost of requiring the end-user to manually install software.
Thus, the complexity of conventional wireless binding schemes lead to product returns and support calls for 1-way wireless HID products. This is very disadvantageous since a single product support call can cost more to service than the total gross margin on the product.
It would be desirable to eliminate some of the disadvantages of conventional binding schemes.